View Full Version : SAS storage
ThEGr33k
16-08-10, 10:43 AM
At work we are looking to build a SAS storage system... Now I have the cards all figured out (man there isnt much info about) and I look like getting 2 8 channel cards for 16 HDD.
The main question is;
You can use SATA HDD on SAS cards, but does this mean that the SATA HDD can run at full duplex when combined with a SAS card? I know SAS card to SAS HDD can do that fine. SO basically can a SATA HDD handle full duplex?
Cheers
Geodude
16-08-10, 10:50 AM
At work we are looking to build a SAS storage system... Now I have the cards all figured out (man there isnt much info about) and I look like getting 2 8 channel cards for 16 HDD.
The main question is;
You can use SATA HDD on SAS cards, but does this mean that the SATA HDD can run at full duplex when combined with a SAS card? I know SAS card to SAS HDD can do that fine. SO basically can a SATA HDD handle full duplex?
Cheers
Wish i was clever enough to know what any of this means :confused: ;)
Jackie_Black
16-08-10, 10:55 AM
Can HDD's ever be full duplex? Surely they either read or write.
I would like to know how fast this thing moves data when you get it finished!!
appollo1
16-08-10, 02:59 PM
Wish i was clever enough to know what any of this means :confused: ;)
phew.....i thought i was the only one that was reading this mysterious code and couldn't work it out!!
ThEGr33k
16-08-10, 03:10 PM
Me too...
Obviously they cant physically do read and write but I think the full duplex helps with data requests etc. We arnt sure what we are going to do yet... Weather 20 500GB 7200rpm SAS discs or something a little smaller but faster RPM...
We have a 16tb SAS and its running dual fibre lines to our other boxes.
So 2gb data transit.
Jackie_Black
16-08-10, 10:04 PM
That's awesome!
At work we are looking to build a SAS storage system... Now I have the cards all figured out (man there isnt much info about) and I look like getting 2 8 channel cards for 16 HDD.
The main question is;
You can use SATA HDD on SAS cards, but does this mean that the SATA HDD can run at full duplex when combined with a SAS card? I know SAS card to SAS HDD can do that fine. SO basically can a SATA HDD handle full duplex?
Cheers
what are you storage requirements? ive been looking at these things for some time so know a fair bit
There are new cards that you can put full SATA disks in then a single SSD drive to accelerate the reads, all depends on your workload. LSI Cachecade and Adaptec MaxIQ are these type of systems.
ThEGr33k
16-08-10, 11:35 PM
Well we currently have a 10 driver SATA Raid 5 and we seem to be getting long access Ques... What we want is high capacity if possible with more speed... Would 7200rpm SAS disks be any faster than 7200rpm SATA discs? Id have thought 10k or even 15k discs are needed to speed I/O which is a potential bottle neck atm?
Other problem is we are trying to keep cost down, pretty hard with storage we are finding, which is why SSD's arnt high on the list, that and stone think that they arnt so good, though im not sure where they are getting that from?
Or alternativley, is there any way to get rid of the access ques with the kit we have? We are using a mobo with 10 SATA build in, would it be better for example to just put some SAS cards in that system? Would that eliviate the bottlekneck?
Well we currently have a 10 driver SATA Raid 5 and we seem to be getting long access Ques... What we want is high capacity if possible with more speed... Would 7200rpm SAS disks be any faster than 7200rpm SATA discs? Id have thought 10k or even 15k discs are needed to speed I/O which is a potential bottle neck atm?
Other problem is we are trying to keep cost down, pretty hard with storage we are finding, which is why SSD's arnt high on the list, that and stone think that they arnt so good, though im not sure where they are getting that from?
Or alternativley, is there any way to get rid of the access ques with the kit we have? We are using a mobo with 10 SATA build in, would it be better for example to just put some SAS cards in that system? Would that eliviate the bottlekneck?
SAS vs SATA at 7200 has hardly any diffrence in it and under some tests has shown to be slightly slower.
Going for 10k vs 7.2k depends a little on the workload itself, also applys to if you go for 3.5" vs 2.5" as the smaller ones have a lower access time than their larger counterparts but come at a cost.
Are you mainly looking at reads or writes on your system, what raid card are you currently using, what is the dataset like, large file reads or lots of small reads etc..
I would not go for SSDs on main storage filers but my angle was the SSD drive on the cards i listed is a read acclerator (ie 64gb of RAID cache), if it breaks then you dont loose anything apart from speed as the data is still all on the disks until you change the drive.
Look at RAID 6 instead of RAID 5 when working with large SATA/SAS filers as the rebuild time will be realy long and you could have a second disk fail while the rebuild is happening, it means more disks but it will save your nuts in the long run also you will probably need your filer to be larger because you will need again more disks to eak out the IOs.
I use the WD RE4-GP disks, they are only 5.4k but they are faster than my 3yr old Seagate ES.2 7.2k disks, there are the RE4 disks which are even cheeper but come with nearly a 25% price hike each.
You would be surprised how much the speed actualy has to do with the raid card itself, a better card may work out well but note you cant transition from one card to another, somtimes if you stay with the same make you can, i have HP cards and you can go up/down the range as long as each card supports the config you had before.
ThEGr33k
17-08-10, 01:53 PM
Interesting stuff.
Right then, to answer your question, the storage will have several Virtual servers and 700 PC's accessing them, so pretty heavy load id guess. We could do with 8+ TB as well.
What you say about the SSD as a buffer, how does that work? It could be something that would be useful and could really keep the ques down id guess. So if you got some literature or can give the low down on that id appreciate it!
The current Discs are all Samsung F3 spinpoint 1TB's, very fast, well fastest SATA HDD you can get atm. By the by, £44 now on Ebuyer!!!!!! Dang.
As a slight side note, with those drives being so cheap, I have 2 in raid 0 at home and am getting pretty nice transfers of 250MB/s Average... im wondering, is it worth adding some more, would I see a speed increase? Also, if I did add some more and rebuild the system with say 4 discs in raid 0, would the backup of windows 7 go back onto the bigger disc space? I know going from single to Raid it wouldnt, but Im fairly certain that was simply down to windows not having the Raid driver in the image?
Cheers for any more help!
As a slight side note, with those drives being so cheap, I have 2 in raid 0 at home and am getting pretty nice transfers of 250MB/s Average... im wondering, is it worth adding some more, would I see a speed increase? Also, if I did add some more and rebuild the system with say 4 discs in raid 0, would the backup of windows 7 go back onto the bigger disc space? I know going from single to Raid it wouldnt, but Im fairly certain that was simply down to windows not having the Raid driver in the image?
Cheers for any more help!
Friends don't let friends use raid 0. You crazy!
ThEGr33k
17-08-10, 02:20 PM
Friends don't let friends use raid 0. You crazy!
I have a backup... :) Could put 4 more and make raid 10 :p
Interesting stuff.
Right then, to answer your question, the storage will have several Virtual servers and 700 PC's accessing them, so pretty heavy load id guess. We could do with 8+ TB as well.
What you say about the SSD as a buffer, how does that work? It could be something that would be useful and could really keep the ques down id guess. So if you got some literature or can give the low down on that id appreciate it!
The current Discs are all Samsung F3 spinpoint 1TB's, very fast, well fastest SATA HDD you can get atm. By the by, £44 now on Ebuyer!!!!!! Dang.
As a slight side note, with those drives being so cheap, I have 2 in raid 0 at home and am getting pretty nice transfers of 250MB/s Average... im wondering, is it worth adding some more, would I see a speed increase? Also, if I did add some more and rebuild the system with say 4 discs in raid 0, would the backup of windows 7 go back onto the bigger disc space? I know going from single to Raid it wouldnt, but Im fairly certain that was simply down to windows not having the Raid driver in the image?
Cheers for any more help!
The speed increase you will see alone going from thoes spinpoint to a proper enterprise SATA disk will be a fair bit, there are several things that the RE4-GP/RE4/ES.2/Constalation disks have that home drives do not but not limited to a major one in the way they fail when in a raid set and NCQ support under high loads, usualy home drives do not need to support this as the request queue is not deep as only one user access the data.
2TB RE4-GP disks are abt £150 each with 5yr warranty and are for raid
At that storage level you are best to go with 8x2TB in a RAID10 with a controler with at least 512Mb but still that will be low on IOPS and you may get better thoughput with a RAID6 overall if you are READ heavy vs WRITE heavy.
You should at least consider upgrading to a 12bay server with a proper raid card.
You need much more IOPS than you have now, you can only do that with either faster 10K/15K disks which the largest is 600Gb i think at the mo and they are expensive cic £350-500each, or with more bays you can get more storage and more IOPS.
You need to work out your current IOPS and then from there we can work things out, are you on windows on linux?
The SSD buffer is as it says, its an extension of the RAID card cache, you need one free bay for it.
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